HPE EVA Storage

IO vs throughput EVA 4400

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IO vs throughput EVA 4400


I posted a message on the VMware forums regarding a slow storage vMotion problem here:


Looking into this made me question my storage speed, I honestly believe the problem to be a VMware issue, but was wondering if someone could confirm a few thoughts of mine regarding EVA performance...

Looking at it basically, I have 24 FSAS 15K disks (Which have several VDisks on them, not just VMware), if I assume they can do 170 IOPS each, then my total throughput is 4080 IOPS.

I am not sure what IO size ESX uses when copying data through storage vmotion (4/8?)

Anyways with the calculations it works out at:

4kb = 15MB's
8kb = 63MB's

Now I assume this throughput figure is a worst case 100% random write/read scenario where the cache modules will not be able to assist. (I believe guest VM access on a single LUN is like random IO, but not sure if a storage vmotion is as it is the same file...?)

The only thing is I have not calculated anything regarding the VRAID level. We are using VRAID 5 which I believe for each write IO actually generates 4 IO's, I am not sure how to incorporate this into my calculations...??

Using the EVA performance monitors on our commandview server I saw a throughput of combined read and write of around 60MB's, when VMware was pushing it, from the output in the VMware post above... I have also correlated this with our san switches which showed a sustained burst of around 50-60MB's between the ESX host port and the EVA controller port.

Does any of this look vaguely correct to an expert?
Víctor Cespón
Honored Contributor

Re: IO vs throughput EVA 4400

24 x 15K disks, assuming a mix of reads and writes, give you about 1800 IOPS in RAID 5.

Then you have to factor the size of those I/Os. 1800 * 4 KB is only 7 MB/s.

You need to capture data with EVAperf and take a look at everything, I/O size, number of I/Os on the disk group, latencies...

Also, recent versions of ESX tend to do very big (> 1 MB) I/Os which does not fit well on an EVA, which is optimized for 128 KB.